1. Field of the Invention
The present invention relates generally to a fuel supply device for an internal combustion engine, and more specifically to a fuel supply device for an internal combustion engine in which a lean mixture gas is supplied by the main carburetor, and at the same time, a fuel-reforming device coupled with an auxiliary carburetor, produces a reformed fuel gas to be supplied to the engine, thereby decreasing the harmful substances in the exhaust gas.
2. Description of the Prior Art
It is a well-known fact that the amount of harmful substances, such as for example, NOx, CO, HC, or the like, present within the exhaust gases emitted from an internal combustion engine depends upon the air-fuel ratio of the mixture within the cylinders, and if the air/fuel ratio is made larger than its theoretical value (in case of NOx, slightly larger than its theoretical value), the quantity of such harmful substances decreases. Therefore, the higher the air/fuel ratio with which the internal combustion engine is driven, the less will be the harmful emissions from the engine. In a common spark-ignition engine, however, when the air/fuel ratio exceeds a value of approximately 17, the engine misfires and a smooth operation becomes virtually impossible. Moreover, along with the emission of unburnt gases, there is a substantial increase in the quantity of harmful substances (mainly HC).